Eight children, age between 4.5 and 19 years were treated with moricizine for supraventricular tachycardia during the last 3 years. The tachycardia was documented by surface electrocardiogram (EGG), and/or by ambulatory ECG in all the children and the mechanism of tachycardia was determined by previously published surface ECG and electrophysiologic criteria in all but one child. Of the eight children, three had atrial ectopic tachycardia, three had automatic junctional ectopic tachycardia, one had atrioventricular (AV) nodal reentry tachycardia and one had atrial reentry. All the children except one had failed trial of two or more antiarrhythmic drugs prior to moricizine therapy. The duration of moricizine therapy ranged from 4 days to 25 months. In three of the eight children (patients 3, 5 and 7), who presented with AV nodal reentrant tachycardia, automatic junctional ectopic tachycardia and atrial ectopic tachycardia, respectively, moricizine therapy was effective in restoring sinus rhythm and controlling the clinical tachycardia. Only one child (patient 1) developed proarrhythmia, an episode of fast, narrow-QRS supraventricular tachycardia lasting for 30 s, on the third day of therapy. This was subsequently confirmed by electrophysiologic study to be AV nodal reentrant tachycardia. The other side effects noted were non-cardiac, not dose-dependant and did not require discontinuation of therapy. Based on our small series and those of others, moricizine, a newer class I anti-arrhythmic agent, has a limited but useful role in the management of recalcitrant type of supraventricular tachycardia, such as ectopic atrial and junctional tachycardia in children.

Propranolol, a first-generation nonselective β-adrenoceptor blocking agent, is commonly used to treat pediatric arrhythmias. Atenolol, relatively long-acting, cardioselective β-adrenoceptor blocking agent, has been successfully used in adults with supraventricular tachycardia (SVT). There is only one report on the use of atenolol in children with SVT, and our report is on the first long-term prospective study to evaluate the use of atenolol in children. A group of 22 children <18 years of age with clinical SVT were enrolled in the study. The tachycardia was documented on electrocardiograms in each case and was confirmed by electrophysiologic studies in some. Once- a-day oral atenolol was started as a monotherapy. Of the 22 children with various types of SVT, 13 (59%) were well controlled on long-term oral atenolol therapy. The effective dose of atenolol ranged between 0.3 and 1.3 mg/kg/day (median effective dose 0.7 mg/kg/day). Five children had some adverse effects. However, none in the successful group of 13 patients required drug discontinuation because of such effects. Once-a-day oral atenolol as a monotherapy is effective and relatively safe for long-term management of SVT during childhood. It is an attractive alternative β- adrenoceptor blocking agent for the management of pediatric arrhythmias.

Supraventrikulinės grįžtamojo ryšio tachikardijos vaikams yra gana dažnas širdies ritmo sutrikimas, kurį sąlygoja papildomi laidumo pluoštai (Kento, Mahaimo), atrioventrikulinės jungties dviejų takų – lėtojo ir greitojo -fiziologiniai ypatumai. Iki gydymo radiodažnine (RD) energija eros, kurios pradžia – 1980 - tieji metai (vaikų amžiuje – 1990 - tieji metai), tachiaritmijų gydymas kėlė daug problemų (ne visuomet efektyvus medikamentinis gydymas, „atviros” širdies operacijos). Mūsų klinikoje pirmoji radiodažninė abliacija (RDA) vaikui atlikta 1991 metais. Pastaruoju metu dėl grįžtamojo ryšio supraventrikulinių tachikardijų (SVT) Kauno klinikose vaikams per metus atliekama apie 20 – 30 tokių procedūrų. Šio gydymo metodo efektyvumas bei mažas komplikacijų skaičius lėmė, kad gydymas RDA tapo pasirinktinu gydymo metodu, gydant SVT. Sukaupta nemažai duomenų apie ankstyvojo ir vėlyvesniojo laikotarpio (praėjus po RDA operacijos 1-29 mėn.) pacientų išgyvenamumą, komplikacijas, širdies ritmo variabilumo pokyčius, kai kuriuos širdies morfometrijos ir funkcijos rodiklius: vožtuvų būklę, įprastinius sistolinę ir diastolinę funkciją atspindinčius rodiklius. Tačiau nėra žinoma apie širdies laidžiosios sistemos, širdies ritmo, ritmo variabilumo pokyčius vėlyvuoju laikotarpiu (praėjus po gydymo RDA daugiau nei dvejiems metams). Pagal šiuos duomenis, retrospektyviai, t.y. jau pagydžius pacientą, galima spręsti apie širdies laidžiosios sistemos ypatumus. Šios žinios reikalingos tiek vaiko... [toliau žr. visą tekstą] / The supraventricular tachycardias (SVT) (atrioventricular reentrant tachycardia due to accessory pathways, atrioventricular nodal reentrant tachycardia) are common in children. It is the most common arrhythmia in Wolff –Parkinson White syndrome. The electrophysiologic – morphologic substrates responsible for both AV node reentrant tachycardia (AVNRT) and AV reentrant tachycardia are thought to be present from birth. Radiofrequency ablation (RFA) successfully eliminates the extra pathway by the application of thermal energy typically leaving only normal conduction. The radiofrequency treatment era started in 1980 (and in 1990 for pediatric patients); the treatment of tachyarrhythmia was problematic until then because drug treatment or open heart surgery were not successful rather frequently. At our clinic, the first RFA for a child was performed in 1991. Nowadays, approximately 20 – 30 RFA procedures per year for children suffering from various types of supraventricular tachycardia are performed in our clinic. This method of treatment is effective and the number of complications is low; therefore, it became a method of choice to treat SVT. Data concerning long-term and short-term survival (1 – 29 months after RFA procedure), complications, changes of heart rhythm variability, certain heart morphometry and functional parameters (including valves function, routine indices of systolic and diastolic function) is rather common. However, alternations of heart conductive system... [to full text]

<p>Det finns få vårdvetenskapliga studier av personer som lever med eller vårdas för olika former av förmakstakykardi. Det saknas även riktlinjer för sjuksköterskor hur de ska omhänderta patienter med förmakstakykardier i lika stor utsträckning som vid andra hjärtsjukdomar. Syftet med detta examensarbete är att beskriva innebörder att leva med och vårdas för förmakstakykardi. Studien har ett livsvärldsperspektiv och ett dialektiskt perspektiv på processen mellan vård och besvär. Data samlades in med kvalitativa intervjuer. Fyra män och tre kvinnor intervjuades. Datan analyserades med en fenomenologisk hermeneutisk metod enligt Lindseth och Norberg (2004). I resultatet belyses processen mellan vård och besvär av förmakstakykardi. Resultatet visar att patienter vars förmakstakykardi har gått över innan de kommer till sjukhus har svårt att få någon diagnos. Resultatet påvisar också att vården inte förser patienterna med den kunskap de behöver i sitt dagliga liv och att det är ett större problem för patienterna att takykardin återkommer än när den pågår. Om dessa aspekter inte tillgodoses så kan det uppstå ett vårdlidande.</p> / <p>There are few studies with a caring science perspective of people who lives or being cared for different forms of supraventricular tachycardia. There is also a lack in guidelines for nurses how to care for patients with supraventrikulär tachycardia in comparison with other heart conditions. The aim of this study is to describe meanings of living with and being under care for supraventricular tachycardia. The study has an lifeworld perspective and a dialectic perspective on the process between caring and inconvenience. Data was collected with qualitative interviews. Four men and three women where interviewed. The data was analyzed using an phenomenological hermeneutic method as described by Lindseth and Norberg (2004). The result enlightens the process between care and inconvenience of supraventricular tachycardia. The result shows that patients with a supraventricular tachycardia that ends before they reach the hospital have difficulties to be diagnosed. The result also points out that the given care dos not provide the patients with the knowledge they need in their daily life and it is a greater problem for the patients that the tachycardia returns then it is when its actually going on. Failing these aspects may inflict a suffering caused by care.</p>

Det finns få vårdvetenskapliga studier av personer som lever med eller vårdas för olika former av förmakstakykardi. Det saknas även riktlinjer för sjuksköterskor hur de ska omhänderta patienter med förmakstakykardier i lika stor utsträckning som vid andra hjärtsjukdomar. Syftet med detta examensarbete är att beskriva innebörder att leva med och vårdas för förmakstakykardi. Studien har ett livsvärldsperspektiv och ett dialektiskt perspektiv på processen mellan vård och besvär. Data samlades in med kvalitativa intervjuer. Fyra män och tre kvinnor intervjuades. Datan analyserades med en fenomenologisk hermeneutisk metod enligt Lindseth och Norberg (2004). I resultatet belyses processen mellan vård och besvär av förmakstakykardi. Resultatet visar att patienter vars förmakstakykardi har gått över innan de kommer till sjukhus har svårt att få någon diagnos. Resultatet påvisar också att vården inte förser patienterna med den kunskap de behöver i sitt dagliga liv och att det är ett större problem för patienterna att takykardin återkommer än när den pågår. Om dessa aspekter inte tillgodoses så kan det uppstå ett vårdlidande. / There are few studies with a caring science perspective of people who lives or being cared for different forms of supraventricular tachycardia. There is also a lack in guidelines for nurses how to care for patients with supraventrikulär tachycardia in comparison with other heart conditions. The aim of this study is to describe meanings of living with and being under care for supraventricular tachycardia. The study has an lifeworld perspective and a dialectic perspective on the process between caring and inconvenience. Data was collected with qualitative interviews. Four men and three women where interviewed. The data was analyzed using an phenomenological hermeneutic method as described by Lindseth and Norberg (2004). The result enlightens the process between care and inconvenience of supraventricular tachycardia. The result shows that patients with a supraventricular tachycardia that ends before they reach the hospital have difficulties to be diagnosed. The result also points out that the given care dos not provide the patients with the knowledge they need in their daily life and it is a greater problem for the patients that the tachycardia returns then it is when its actually going on. Failing these aspects may inflict a suffering caused by care.

No description available.

Abstract Approximately 1-2 percent of the world population lives with various heart rhythm disorders of supraventricular nature. These arrhythmias can alter the patient's lifestyle and negatively affect the balance between the demands of daily life and functional abilities. To diagnose paroxysmal supraventricular tachycardia (PSVT) can be difficult due to spontaneity of the episodes and the transience nature of the symptoms. Finding the right treatment can also pose a challenge because some of the medicines used are associated with increased toxic risks and requires close monitoring of the patient through regular blood tests. Some patients experience recurrence of symptoms despite optimal treatment measures and adherence to treatment and self-care recommendations.  Studies have shown that patients’ prior knowledge regarding these diagnoses is low. The nurse has a crucial role of informing and making sure that patients receive education in among other things self-care as well as information regarding disease and drugs related complications etc. There is a mutual interaction between daily life and functional health status where daily life makes demands on functional abilities at the same time as these affect how an individual lives their daily lives. In order to experience quality of life and health, the balance between these two must be maintained. The nurse has a pivot role in assisting the patient maintain the balance.  The study’s aim was to highlight the effects of living with supraventricular tachycardia (SVT) on the patient's daily life. The method chosen was literature review. Original articles were obtained from established databases such as PubMed and CINAHL, and the results from 17 articles were analyzed using content analysis. This means that the text was read several times in order to familiarize with the content. Different units were identified and the categories as well as sub-categories were coded. These formed the basis of the headings and subheading used to present the results. Four categories and ten sub-categories were identified from the studies.  Studies show that SVT has negative effects on the patients’ daily life. Symptoms cause anxieties and uncertainties that lead to mental and emotional stress. Some patients withdraw from participating in the social activities for fear of provoking the attacks whereas others are forced to give up participation due to among other things fatigue that results from symptoms attacks. Family life is sometimes disrupted since the symptoms can lead to fatigue that negatively affects family life in that patients do not have the energy to participate in activities in their home or to live up to other requirements of their daily lives.  The diagnosis can even affect economy since patients are forced to cut down on working hours or go into early retirement. Other patients lost their employment due to frequent hos-pital visits or inability to fulfill their duties. Physical activities as well as well-being are negatively affected too in that some patients show signs of impaired physical activities. Patients use different coping strategies such as planning their daily lives around the symp-tomatic periods. In conclusion it is suffice to state that SVT has negative effects on the patients’ daily life. The Patients would benefit from a well-structured and person centered patient education.

No description available.

BACKGROUND: There are only limited data about peri-interventional pain during cardiac electrophysiological procedures without analgosedation. In this study, peri-interventional pain and recollection of it after the intervention were evaluated. METHODS: A total of 101 patients (43 electrophysiological/ablation procedures and 58 device surgeries) reported pain on a numerical rating scale (NRS; 0-10) before (pre), during (peri), and after (post) the intervention. Maximum pain (maxNRS) and the average of pain (meanNRS) were used for statistical analysis. Peri-interventional pain was compared with postinterventional data of the recollection of peri-interventional pain (peri-post). Patients were allocated into 2 groups (with 51 and 50 patients, respectively) to evaluate the mode of patient-staff interaction on pain recollection. Depressive, anxiety, and somatic symptom scales (Patient Health Questionnaire-15, Generalized Anxiety Disorder-7, and Patient Health Questionnaire-15) were used to analyze their influence on pain recollection. RESULTS: In total, 49.6% of patients (n = 50) complained of moderate to severe pain (maxNRS) at least once during the procedure. The comparison between peri and peri-post data revealed the following (median (range)-maxNRS, peri: 3 (0-10) versus peri-post: 4 (0-9) (ns), and meanNRS, peri: 1.4 (0-7) versus peri-post: 2.0 (0-6) (ns). The mode of patient-staff interaction had no influence on pain. No effect was found for psychosocial factor concerning pain and the recollection of pain. The results of the linear regression showed no influence of low-dose midazolam on recollection of pain. CONCLUSION: Half of the patients reported moderate to severe pain at least once during cardiac electrophysiological procedures without analgosedation. However, on average, patients reported only low pain levels. Postinterventional derived data on discomfort reflect the peri-interventional situation.:Inhaltsverzeichnis 1 Einführung in die Thematik 1.1 Hintergrund zur Thematik 1.2 Inhaltlicher Gegenstand 1.3 Fragestellung 2 Publikation 3 Zusammenfassung der Arbeit 4 Literatur I Darstellung des eigenen Beitrages II Selbstständigkeitserklärung III Lebenslauf IV Publikationen V Danksagung

Le nœud auriculoventriculaire (AV) joue un rôle vital dans le cœur normal et pathologique. Il connecte les oreillettes aux ventricules et, grâce à sa conduction lente, génère un délai entre les contractions auriculaire et ventriculaire permettant d’optimiser le pompage sanguin. Sa conduction lente et sa longue période réfractaire font du nœud AV un filtre d’impulsions auriculaires lors de tachyarythmies assurant ainsi une fréquence ventriculaire plus lente favorable au débit cardiaque. L’optimisation de ce filtrage est une cible dans le traitement de ces arythmies. Malgré ce rôle vital et de nombreuses études, le nœud AV demeure l’objet de plusieurs controverses qui en rendent la compréhension laborieuse. Nos études expérimentales sur des préparations isolées de cœurs de lapin visent à apporter des solutions à certains des problèmes qui limitent la compréhension des propriétés fréquentielles du nœud AV. Le premier problème concerne la définition de la propriété de récupération nodale. On s’accorde généralement sur la dépendance du temps de conduction nodale (intervalle auriculo-Hissien, AH) du temps de récupération qui le précède mais un débat presque centenaire persiste sur la façon de mesurer ce temps de récupération. Selon que l’on utilise à cette fin la longueur du cycle auriculaire (AA) ou l’intervalle His-auriculaire précédent (HA), la même réponse nodale montre des caractéristiques différentes, un paradoxe à ce jour inexpliqué. Le temps de conduction nodale augmente aussi avec le degré et la durée d'une fréquence rapide, un phénomène appelé fatigue. Or, les caractéristiques de la fatigue mesurée varient avec l’indice de récupération utilisé (AA vs. HA). De plus, une troisième propriété appelée facilitation qui entraîne un raccourcissement du temps de conduction diffère aussi avec l’indice de récupération utilisé. Pour établir l’origine de ce problème, nous avons déterminé les différences entre les courbes de récupération (AH compilé en fonction du AA ou HA) pour 30 états fonctionnels nodaux différents. Ces conditions étaient obtenues à l’aide de protocoles permettant la variation du cycle de base (BCL) et du cycle prétest (PTCL), deux paramètres connus pour altérer la fonction nodale. Nous avons pu établir que pour chaque état fonctionnel, la forme de la courbe de récupération et le niveau de fatigue étaient les mêmes pour les deux indices de récupération. Ceci s’applique aussi aux données obtenues à des BCL et PTCL égaux comme dans les protocoles de stimulation prématurée conventionnels couramment utilisés. Nos résultats ont établi pour la première fois que les propriétés nodales de récupération et de fatigue sont indépendantes de l’indice de récupération utilisé. Nos données montrent aussi que les différences entre les courbes de récupération en fonction de l’indice utilisé proviennent d’effets associés aux variations du PTCL. Notre deuxième étude établit à partir des mêmes données pourquoi les variations du PTCL altèrent différemment les courbes de récupération selon l’indice utilisé. Nous avons démontré que ces différences augmentaient en proportion directe avec l’augmentation du temps de conduction au battement prétest. Cette augmentation cause un déplacement systématique de la courbe construite avec l’intervalle AA vers la droite et de celle construite avec l’intervalle HA vers la gauche. Ce résultat met en évidence l’importance de tenir compte des changements du temps de conduction prétest dans l’évaluation de la fonction nodale, un paramètre négligé dans la plupart des études. Ce résultat montre aussi que chacun des deux indices a des limites dans sa capacité d’évaluer le temps de récupération nodale réel lorsque le temps de conduction prétest varie. Lorsque ces limites sont ignorées, comme c’est habituellement le cas, elles entraînent un biais dans l’évaluation des effets de fatigue et de facilitation. Une autre grande difficulté dans l’évaluation des propriétés fréquentielles du nœud AV concerne son état réfractaire. Deux indices sont utilisés pour évaluer la durée de la période réfractaire nodale. Le premier est la période réfractaire efficace (ERPN) définie comme l’intervalle AA le plus long qui n’est pas conduit par le nœud. Le deuxième est la période réfractaire fonctionnelle (FRPN) qui correspond à l’intervalle minimum entre deux activations mesurées à la sortie du nœud. Paradoxalement et pour des raisons obscures, l’ERPN augmente alors que la FRPN diminue avec l’augmentation de la fréquence cardiaque. De plus, ces effets varient grandement avec les sujets, les espèces et l’âge. À partir des mêmes données que pour les deux autres études, nous avons cherché dans la troisième étude l’origine des variations fréquentielles de l’ERPN et de la FRPN. Le raccourcissement du BCL prolonge l’ERPN mais n’affecte pas la FRPN. L’allongement de l’ERPN provient principalement d’un allongement du temps de conduction prétest. Un PTCL court en comparaison avec un BCL court allonge encore plus substantiellement le temps de conduction prétest mais raccourcit en même temps l’intervalle His-auriculaire, ces deux effets opposés s’additionnent pour produire un allongement net de l’ERPN. Le raccourcissement de l’intervalle His-auriculaire par le PTCL court est aussi entièrement responsable pour le raccourcissement de la FRPN. Nous avons aussi établi que, lorsque la composante du temps de conduction prétest est retirée de l’ERPN, un lien linéaire existe entre la FRPN et l’ERPN à cause de leur dépendance commune de l’intervalle His-auriculaire. Le raccourcissement combiné du BCL et du PTCL produit des effets nets prévisibles à partir de leurs effets individuels. Ces effets reproduisent ceux obtenus lors de protocoles prématurés conventionnels. Ces observations supportent un nouveau schème fonctionnel des variations fréquentielles de l’ERPN et de la FRPN à partir des effets distincts du BCL et du PTCL. Elles établissent aussi un nouveau lien entre les variations fréquentielles de l’ERPN et de la FRPN. En conclusion, la modulation fréquentielle de la fonction du nœud AV provient de la combinaison d’effets concurrents cumulatifs liés au cycle de base et non-cumulatifs liés au cycle prétest. Ces effets peuvent être interprétés de façon consistante indépendamment de l’indice de récupération en tenant compte des changements du temps de conduction au battement prétest. Les effets fréquentiels disparates sur l’ERPN et la FRPN sont aussi grandement liés aux changements du temps de conduction prétest. Lorsque l’analyse tient compte de ce facteur, l’ERPN et la FRPN montrent des variations parallèles fortement liées à celles de l’intervalle His-auriculaire. Le nouveau schème fonctionnel des propriétés fréquentielles du nœud AV supporté par nos données aidera à mieux cibler les études sur les mécanismes cellulaires contrôlant la modulation fréquentielle nodale. Nos données pourraient aider à l’interprétation et au contrôle des réponses nodales diverses associées aux tachyarythmies supraventriculaires et à leur traitement pharmacologique. En bref, nos travaux supportent une compréhension factuelle améliorée du comportement fréquentiel du nœud AV, un domaine aux applications multiples en rythmologie cardiaque. / The atrioventricular (AV) node is the sole electrical connection between atria and ventricles, and is of utmost importance in both normal and perturbed cardiac function. Through slow conduction, it generates a delay between atrial and ventricular systoles, thereby optimising cardiac output. The AV node also has a long refractory period which confers it a filtering role during supraventricular tachyarrhythmias. Because of this ventricular rate watchdog role, the AV node has become a primary therapeutic target in atrial fibrillation, a frequent arrhythmia with major clinical burden. Not withstanding intense research, understanding of AV nodal function remains restrained by many controversies, some of which have persisted for almost a century. Major obstacles concern the definition of nodal recovery time and nodal refractoriness. The objective of our studies is to untangle some of these controversies regarding rate-dependent AV nodal function in an experimental model of superfused rabbit heart preparations. Our first study concerns the definition of AV nodal recovery time used to assess rate-dependent nodal function. The dependence of conduction time through the node (atrio-His interval; AH) on time elapsed since last activation i.e., recovery time (RT), is a well accepted fact but its assessment is controversial for nearly a century. This problem arises from the fact that the nodal recovery function shows different characteristics depending upon whether RT is assessed from the preceding atrial cycle length (AA) or His-atrial (HA) interval. Moreover, the rate- and time-dependent increase in AH, known as fatigue, also shows different characteristics depending on RT index used. Furthermore, the third rate-dependent AV nodal property known as facilitation and that tends to shorten AH with penultimate cycle length, is obviously present or virtually absent when studying it with HA or AA index, respectively. Our first study sought to identify the source of this paradoxical apparent dependence of nodal rate-dependent properties on selected RT index. For this purpose, we varied two known independent modulators of AV nodal function, the basic (BCL) and pretest cycle length (PTCL), in 30 different combinations and assessed how the resulting 30 nodal functional states alter the recovery and the fatigue property as assessed with both recovery indexes. We found that, for each functional state, the shape of the nodal recovery curve and the level of fatigue was identical regardless of selected recovery index. We thus documented for the first time that recovery and fatigue properties are consistent whether assessed with HA or AA. However, we also found that PTCL effects appeared different on the two recovery curve formats. In a second study, using the same data, we investigated the origin of PTCL related variations of nodal recovery curves constructed with different recovery indexes. We found that PTCL shortening induced rightward AA curve shifts and leftward HA curve shifts proportional to the increase in pretest conduction time. Moreover, these curve shifts affected all data points equally. This finding suggests that both AA and HA indexes are biased by increases in pretest conduction time. These increases appeared to delay nodal recovery for an identical AA, and to hasten nodal recovery for an identical HA. Uncontrolled changes in pretest conduction time during fast rates thus produce apparent different effects depending on nodal recovery index. Taking into account changes in pretest conduction time results in unified rate-dependent nodal conduction properties regardless of chosen recovery index. Another major problem in AV nodal physiology relates to rate-dependent changes in nodal refractoriness. Two indexes of nodal refractoriness, effective (ERPN) and functional (FRPN) refractory periods, are commonly determined. ERPN and FRPN correspond to the longest AA resulting in nodal block and shortest interval between successive His bundle activations, respectively. For unclear reasons, increasing rate typically results in ERPN prolongation but FRPN shortening, and these effects vary greatly with individuals, ages and species. In a third study, we assessed the functional origin of rate-induced changes in ERPN and FRPN. BCL shortening prolonged ERPN but did not significantly affect FRPN. This ERPN prolongation mainly arose from an increase in pretest conduction time. PTCL shortening also prolonged the pretest conduction time and hence ERPN, but this prolongation was partly counterbalanced by a decrease in the His-atrial subinterval at ERPN. Similar PTCL-induced His-atrial shortening also fully accounted for FRPN shortening. Notably, we found that when ERPN is corrected for the increase in pretest conduction time, ERPN and FRPN vary in parallel according to their respective His-atrial subintervals. Combined BCL and PTCL shortening, including those corresponding to standard commonly used protocols, result in net changes in refractory measures predictable from the sum of their individual effects. These observations not only support a new functional scheme for rate-dependent AV nodal refractoriness but also establish a relationship between ERPN and FRPN which, for a long time, were thought to reflect different nodal properties. In conclusion, rate-dependent AV nodal function reflect the net sum of concurrent yet independent cumulative and non-cumulative effects arising from BCL and PTCL changes, respectively. Nodal recovery and fatigue properties are independent of recovery index. Rate-induced non-cumulative variations in nodal recovery curves originate from changes in pretest conduction time and reflect current limitations of recovery indexes to precisely measure exact nodal recovery time. Changes in pretest conduction time also explain opposite rate-induced changes in ERPN and FRPN. When these changes are taken into account, FRPN and ERPN vary in parallel with heart rate and largely depend on His-atrial interval. These data support a new functional model of rate-dependent nodal conduction and refractoriness, which may help guide studies on underlying cellular and ionic mechanisms as well as on nodal behaviour during supraventricular tachyarrhythmias.